Questions about the BASICtools and MakeItC
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Joined: Fri Oct 19, 2012 5:11 am


Post by YahooArchive »

>from the support line
>I am trying to use an external reset - so I connect external TTL
device directly to RST pin on Coridium, and sending 5V or 0V, but
this somehow create a problem with all circuit. I am controlling
digital potentiometer with your device and when RST pin connected to
external TTL signal - potentiometer just stop to work without RST
connection its work fine...

The RESET signal is a open collector signal. In other words it may be
pulled low, but not driven high. There is a resistor that pulls the
line high. And any of the reset sources can pull it low, the
capacitor for power on, the push button, the DTR line.

So you can add another RESET source, but it can only pull down. If it
drives the line high, it will interfere with the other RESET sources,
as you are seeing.

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